1. Field of Invention
The present invention relates to an electrode, a method to form an electrode, a thin-film transistor, an electronic circuit, an organic electroluminescent element, a display, and electronic equipment.
2. Description of Related Art
Related art organic thin-film field-effect transistors using organic semiconductor materials may be potential substitutions for thin-film field-effect transistors using inorganic materials represented by silicon. Typical related art organic thin-film transistors have a structure using gold for their source and drain electrodes, as described in Rogers et al. 24 Apr. 2001. Proceedings of the National Academy of Sciences. Vol. 98. No. 948354840, for example.
Specifically, a thin-film transistor described in Rogers et al. 24 Apr. 2001. Proceedings of the National Academy of Sciences. Vol. 98. No. 948354840 has a structure in which a gate electrode is formed by etching indium tin oxide (ITO) by photolithography on a polyethylene terephthalate substrate and a gate insulating layer is made of organic siloxane and silicon nitride. Then, a gold thin film is formed by vapor deposition and patterned by microcontact printing, so as to form source and drain electrodes. Subsequently, an organic semiconductor layer (p-type organic semiconductor layer) is formed by vapor deposition, which completes the transistor.
The organic transistor described in Rogers et al. 24 Apr. 2001. Proceedings of the National Academy of Sciences. Vol. 98. No. 948354840, however, leaves room for improvement in terms of cost, since the source and drain electrodes are formed by depositing and etching a costly gold thin film. If an alternative economical metal, such as aluminum, is used to form the electrodes, there arises a problem of lowering transistor properties as a result of a large barrier at the interface of the source electrode and the organic semiconductor layer, which results in low efficiency in injecting carriers (holes).